Remove unused function `ofLatestCheckpoint` from BlockHeight

Sources/ZcashLightClientKit/Checkpoint/Checkpoint.swift

@@ -84,13 +84,3 @@ extension Checkpoint: Decodable {
         return ret
     }
 }
-
-public extension BlockHeight {
-    /// Useful when creating a new wallet to reduce sync times.
-    /// - Parameters:
-    ///  - zcashNetwork: Network to use for the block height.
-    /// - Returns: The block height of the newest checkpoint known by the SDK.
-    static func ofLatestCheckpoint(network: ZcashNetwork) -> BlockHeight {
-        Checkpoint.birthday(with: BlockHeight.max, network: network).height
-    }
-}